[PATCH] Create ".dynamic" section earlier

[PATCH] Create ".dynamic" section earlier

[Fred Fish]

When testing gdb for various mips*-elf toolchains I'm getting link errors like the following
edited message:

  gdb compile failed, ld: gdb1555.so: The first section in the PT_DYNAMIC segment is not the .dynamic section
  ld: final link failed: Bad value
  collect2: ld returned 1 exit status

Attached is a patch that fixes it, though I'm not sure it is the best
way to handle the issue.

-Fred

2006-06-05  Fred Fish  <fnf@specifix.com>

	* elflink.c (_bfd_elf_link_create_dynamic_sections): Create
	the ".dynamic" section earlier, so it ends up as the first
	section in the PT_DYNAMIC segment, a condition enforced by
	the linker.

Index: binutils/bfd/elflink.c
===================================================================
RCS file: /cvsroots/latest/src/binutils/bfd/elflink.c,v
retrieving revision 1.1.1.16
diff -u -p -r1.1.1.16 elflink.c
--- binutils/bfd/elflink.c	28 May 2006 10:10:47 -0000	1.1.1.16
+++ binutils/bfd/elflink.c	5 Jun 2006 16:39:06 -0000
@@ -215,6 +215,11 @@ _bfd_elf_link_create_dynamic_sections (b
       || ! bfd_set_section_alignment (abfd, s, bed->s->log_file_align))
     return FALSE;
 
+  s = bfd_make_section_with_flags (abfd, ".dynamic", flags);
+  if (s == NULL
+      || ! bfd_set_section_alignment (abfd, s, bed->s->log_file_align))
+    return FALSE;
+
   s = bfd_make_section_with_flags (abfd, ".dynsym",
 				   flags | SEC_READONLY);
   if (s == NULL
@@ -226,11 +231,6 @@ _bfd_elf_link_create_dynamic_sections (b
   if (s == NULL)
     return FALSE;
 
-  s = bfd_make_section_with_flags (abfd, ".dynamic", flags);
-  if (s == NULL
-      || ! bfd_set_section_alignment (abfd, s, bed->s->log_file_align))
-    return FALSE;
-
   /* The special symbol _DYNAMIC is always set to the start of the
      .dynamic section.  We could set _DYNAMIC in a linker script, but we
      only want to define it if we are, in fact, creating a .dynamic

Re: [PATCH] Create ".dynamic" section earlier

[H. J. Lu]

On Fri, Jun 09, 2006 at 10:14:24AM -0400, Fred Fish wrote:
> When testing gdb for various mips*-elf toolchains I'm getting link errors like the following
> edited message:
> 
>   gdb compile failed, ld: gdb1555.so: The first section in the PT_DYNAMIC segment is not the .dynamic section
>   ld: final link failed: Bad value
>   collect2: ld returned 1 exit status
> 
> Attached is a patch that fixes it, though I'm not sure it is the best
> way to handle the issue.
> 

I have seen similar one before. I thought I fixed it with

http://sourceware.org/ml/binutils/2006-05/msg00508.html

I may have missed this one. Do you have a testcase?


H.J.

Re: [PATCH] Create ".dynamic" section earlier

[Fred Fish]

On Friday 09 June 2006 11:03, H. J. Lu wrote:
> I may have missed this one. Do you have a testcase?

Here's a simple one:

$ cat main.c
main ()
{
}

$ mips-elf-gcc -shared -o main main.c -Tidt.ld
/links/opt-local/latest/trunk/bin/../lib/gcc/mips-elf/4.2.0/../../../../mips-elf/bin/ld: main: The first section in the PT_DYNAMIC segment is not the .dynamic section
/links/opt-local/latest/trunk/bin/../lib/gcc/mips-elf/4.2.0/../../../../mips-elf/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status

Re: [PATCH] Create ".dynamic" section earlier

[H. J. Lu]

On Fri, Jun 09, 2006 at 11:40:09AM -0400, Fred Fish wrote:
> On Friday 09 June 2006 11:03, H. J. Lu wrote:
> > I may have missed this one. Do you have a testcase?
> 
> Here's a simple one:
> 
> $ cat main.c
> main ()
> {
> }
> 
> $ mips-elf-gcc -shared -o main main.c -Tidt.ld
> /links/opt-local/latest/trunk/bin/../lib/gcc/mips-elf/4.2.0/../../../../mips-elf/bin/ld: main: The first section in the PT_DYNAMIC segment is not the .dynamic section
> /links/opt-local/latest/trunk/bin/../lib/gcc/mips-elf/4.2.0/../../../../mips-elf/bin/ld: final link failed: Bad value
> collect2: ld returned 1 exit status

I don't have mips-elf-gcc. Can you provide all linker inputs, including
idt.ld?


H.J.

Re: [PATCH] Create ".dynamic" section earlier

[Fred Fish]

On Friday 09 June 2006 12:38, H. J. Lu wrote:
> I don't have mips-elf-gcc. Can you provide all linker inputs, including
> idt.ld?

OK.

Here's how to reproduce it:

    $ tar -xvzf link-kit.tgz
    crtbegin.o
    crtend.o
    crti.o
    crtn.o
    idt.ld
    libgcc.a
    link.sh
    main.o
    $ sh -x link.sh
    + mips-elf-ld -EB -shared -o main crti.o crtbegin.o main.o libgcc.a crtend.o crtn.o -Tidt.ld
    mips-elf-ld: main: The first section in the PT_DYNAMIC segment is not the .dynamic section
    mips-elf-ld: final link failed: Bad value

I'll email you the link-kit.tgz file separately.

-Fred

Re: [PATCH] Create ".dynamic" section earlier

[Daniel Jacobowitz]

On Fri, Jun 09, 2006 at 11:40:09AM -0400, Fred Fish wrote:
> $ mips-elf-gcc -shared -o main main.c -Tidt.ld
> /links/opt-local/latest/trunk/bin/../lib/gcc/mips-elf/4.2.0/../../../../mips-elf/bin/ld: main: The first section in the PT_DYNAMIC segment is not the .dynamic section
> /links/opt-local/latest/trunk/bin/../lib/gcc/mips-elf/4.2.0/../../../../mips-elf/bin/ld: final link failed: Bad value
> collect2: ld returned 1 exit status

This problem, of course, only arises because the .dynamic section is
not in your linker script.  If you were using the standard linker
scripts generated by the ld build process, it would probably work.

The problem is that the parameter file for mips-elf has
GENERATE_SHLIB_SCRIPT=yes, so -shared is allowed by the linker, but
you're using a handwritten (from libgloss) linker script that doesn't. 
So orphan placement is kicking in.

-- 
Daniel Jacobowitz
CodeSourcery